Electric current rectifier



Jun. 29, 1935. H. F. FRUTH ELECTRIC CURRENT RECTIFIER Filed Jan. 9, 1934 INVENTOR Patented `an. 29, 1935 UNITED STATES PATENT OFFICE l 1,989,311 ELECTRIC CURRENT RECTIFIER Hal F. Fruth, Indianapolis,- Ind., assignor to P. R. Mallory & Co., Incorporated, Indianapolis, Ind., a corporationv of Indiana Application January 9,

16 Claims.

and blocking, current. in the reverse direction. More particularly, the invention relates torectifiers of the type describedin the copending application of Samuel Ruben', Serial No. 665,869 filed April 13, 1933 `and assigned to the same assignee.

General-objects of the invention are the provision of such couples having improved characteristics, which are c icient, economical and .readily manufactured, and have long vservice lives; the provision in such couples of sealing meansto prevent deterioration of the couples due to moisturc,oxidization, and destruction due viding means for supplying to' the' couple during the' operation elemental sulphur, selenium or tellurium in vapor form; and structural em- 30 bodiments of the devicewhich are readily kconstructed and allow emcient use and operation thereof. y

A more specific object of the invention is the provision in such a. device for the usual centrally 35 disposed assembly bolt of a bushing or collar of brous material such as bre or cardboard impregnated with a material adapted to supply to the couple during operation thereof a replenishing amount in vapor form of at least one of the 40 elements sulphur, selenium and tellurium.

Another object of the invention is the provision in such a device of a layer of fabric material such as fibrous thread impregnated with a sealing compound such as a plasticized lacquer covering the exposed surfaces of the couple.

Other objects of the invention will in part be obvious andwill in part appear hereinafter.

The invention accordingly comprises the features of construction, combination of elements,

u l 5 and arrangement of parts, which will be exemplied in the construction hereinafter set forth and the scope of the invention which will be indicated in the claims.

For a fuller understanding of the nature and 55 objects of the invention reference should be had property of conductingcurrent in one direction to salt water spray, etc., while additionally pro- 1934, Serial No. 705,850

to the following detailed description taken in, connection with the accompanying drawing, in which:

, Fig. l is a perspective view of the device of the present invention;r

Fig. 2 is an elevational sectional view with parts broken away of one form of the device depicted in Fig. 1; and

Fig.3 is an elevational sectional view with parts broken away of another form of the device l;

depicted in Fig. 1. Many commercial dry rectiers utilizecouples wherein the electropositive electrode element is formed of magnesium and the other electrode element has asurface of electronegative material l5 including at least one of the elements sulphur, selenium and tellurium in contact with the electropositive electrode element. By way of example, in using an electrode of magnesium in surface contact with cupric'sulphide a rectifying 20 layer is forrried therebetween which is believed to be magnesium sulphide. While such couples are initially stable and capable of satisfactory operation under -normal operating conditions for a time, it has been found that eventually the internal resistance increased, cupric sulphide was reduced to cuprous sulphide and/or to copper, I4 an insulating oxide of magnesium was formed, internal heating was increased,` copper oxide wasformed and leaky and short circuited junctions .30 were frequently developed. .It was also found that in transoceanic transportation ofthe devices salt water spray caused corrosion and'destruction of the units. Some of these dilculties appeared. to develop from moisture in the atmosphere and others from the oxidizing eifect thereof. Sealing, while tending to solve some of these problems, increased the heating with a consequent tendency to oxidize the sulphide Flrlayer. 'Ihe use of sealing varnishes orlacquers was attended by further 40 difficulties in that alternate jheating and cooling soon caused the sealing'f-l compound to becom brittle, eventually to crack and to leak.

These and other difficulties of the prior art are efficiently overcome by the present invention. By using a fabric material such as fibrous thread, for example, cotton thread, impregnated with a sealing compound, for example a plasticized varnish or lacquer, the difficulties due to salt water spray and gases, atmospheric oxidation and moisture deterioration, and cracking and leakage of sealing coatings are avoided. Avoidance .of at least some of these features isaugmented by a collar or bushing about the transflxing assembly bolt. The collar Vor bushing is formed of a fibrous material, preferably from fibre or cardboard, and is impregnated with a material i'ncluding at least one of the elements sulphur, selenium and tellurium. Heat developed by operation of the rectier causes the formation of a vapor of the element or elements impregnated into the bushing which aids; in the exclusion of an oxidizing atmosphere, prevents reduction of the rectifying layer constituting a. compound thereof and acts as a replenishing supply of the element or elements aiding in the maintenance of the rectifying layer thereby insuring continued efficient operation of the rectifier.

Referring to the drawing likenumerals refer to like parts throughout. A structural embodiment of rectiers of the type indicated which incorporates the features of the present invention is depicted. 'I'he rectifier makes use of a plurality of elemental unilaterally conductive couples -10, eachof which includes an electropositive electrode element 11 of any suitable electropositive material such as, for example, aluminum or magnesium which has been slightly oxidized; an electronegative electrode element 12 of any suitable electronegative material, preferably one which has a surface of an electronegative material including at least one of Vthe elements sulphur, selenium and tellurium, for example cupric sulphide; and a ,layer 13 of nonpolarizing material, such as a disc of carbonized nickel. Each of the couples 10 are provided with a pair of terminal plates 14 and 15 and as shown in the drawing when a plurality of couples are mounted in series, the terminal plate 15 of the preceding couple is placed in contact with the electropositive electrode element 11 of the succeeding couple, thereby making unnecessary the use of an additional terminal plate 14 for the succeeding couple. 'Ihe end terminal plates, as shown, are provided with projecting feet 16, 16 for ready mounting of the unit.

The electrodes 11 and' 12 and layers 13 of nonpolarizing material are apertured as shown and mounted upon an assembly bolt 17 surrounded by a collar or bushing 18 of brous material,

preferably nbre or cardboard, impregnated with a Vmaterial including at least one of the elements sulphur, selenium and tellurium.

As previously explained, this collar or bushing provides a source for at least one of the elements sulphur, selenium and tellurium in vapor form during the operation of the rectifier unit. This bushing may provide suitable insulation to prevent short-circuiting of the couples by the bolt 17 as indicated in Fig. V2, and cooperates with the end terminal plates and end plates 19, 19 to form an internal seal for the couple which is augmented by the formation of the vapor during the operation of the device. Such a bushing will perform its bushing functions satisfactorily at operating temperatures while being capable of carrying suflicient material including at least one of the elements sulphur, selenium and tellurium to provide a source for sufficient vapor throughout desirably long periods of efficient operation of the device.

However, as depicted in Fig. 3, spacing may be used to prevent short-circuiting by the bolt 17, the elements being held in -their relative positions by the clamping action of the bolt and sealing of the interior of the rectifier unit being obtained by the end plates 19, 19, which is augmented by the vapor formed during operation, the impregnated collar 18' serving as a source for this vapor.

Various methods may be followed in preparing the collars or bushings of the present invention. For example, a porous bre tube may be immersed in molten sulphur at a temperature of about 130 C. until all bubbling ceases. This may require an immersion for about 30 minutes. Inaddition, the tube may be vacuum impregnated with the desired material or may be impregnated with a solution of sulphur dissolved in carbon bisulphide. Other similar and suitable methods will readily occur to those skilled in the art.

External sealing of the couples is obtained by the use of a layer 20 of fabric material impregnated with a sealing compound. The layer 20 is. preferably in the form of layers of brous thread 21, such as cotton thread, impregnated preferably with a plasticized varnish or lacquer as shown. 'I'he thread may be saturated with the sealing compound and then wound about the couples to constitute layers thereof, but is preferably wound about the couples in unsaturated condition after which the rectier unit is dipped in or sprayed with the plasticized varnish or lacquer. It will be obvious that this type of external sealing may be used on dry rectier units of any type falling within the definition indicated above, as well as being suitable for use on rectifying units utilizing the particular types of couples described. Rectiers externally sealed in the manner indicated above were submitted to an 80 per cent humidity test and after six weeks were found to be in perfect condition. They were also submitted to a salt spray test for a ten day period and were found to be in perfect condition at the end of that time. Similar units provided with old style coatings of lacquerssubmitted to the same tests were found to have failed after a two day period and in certain instances Were found to fail in a shorter time.

As is wellknown in the art and more fully set forth in the application of Samuel Ruben identified above, many elements and combinations thereof can be used in the formation of rectifler electrodes. 'Ihose using electrodes having a surface of a relatively electronegative material including one or more of the elements sulphur, selenium and tellurium are improved in operation by the use of bushings of the present invention. It is preferable, but not essential, that those of the elements sulphur, selenium and tellurium present in the electronegative material should be present in the electronegative material with which the bushings are impregnated. However, for example, when the electronegative electrode element has a surface of cupric sulphide, a bushing may be used which is impregnated with a material including selenium whereby during operation of the device vaporized selenium is supplied to the device for the formation of a selenide, which, with the sulphide, will constitute a rectifying layer.

In accordance with the present invention any known type of dry rectifier falling within the general class indicated by the definition of unilaterally conductive couple can be improved as indicated by the use of an internally disposed tube of fibrous material impregnated with a material adapted to supply to the couple during operation a v'apor of the same element which is a component of the compound constituting the rectifying layer. n

It will thus be seen that the present invention efficiently attains the objects set forth above and since certain changes may be made 'in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that all matter contained in theabove description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent,- is:

1. In electric current rectiflers and the like, of the dry surface Contact variety, the combinaf tion with a unilaterally conductive couple comprising a relatively electropositive electrode, another electrode having a surface of a relatively electronegative material each of which is adapted to supply at least one element for the electrochemical formation and maintenance of a cornpound constituting an inverse current-blocking film at their junction; of a centrally disposed tube of fibrous material impregnated with a material adapted to supply to said couple during operation thereof a vapor of at least one ofsaid elements, and a layer of fabric material impregnated with a sealing compound covering the exposed surfaces of said couple.

2. In electric current rectifiers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple comprising a relatively electropositive electrode, another electrode having a surface of a relatively electronegative material including at least one element chosen from the group sulphur, selenium and tellurium; of a centrally disposed tube of fibrous material impregnated with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated vwith a sealing compound covering, the exposed surfaces of said couple.

3. Inelectric current rectiers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple comprising a relatively electropositive electrode, another electrode having` a surface of a relatively electronegative material including at least one element chosen from the group sulphur, selenium and tellurium, and means to secure said electrodes in surface contact; of a collarrof brous material about said securing means impregnated with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated with a sealing compound coveringthe exposed surfaces of said couple.

4. In electric current rectifiers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple comprising a centrally apertured electrode of relatively electropositive material, another centrally apertured electrode having a surface of a relatively electronegative material including at least one`element chosen from the group sulphur, selenium and tellurium, terminal plates disposed on the ends of said couple, and centrally disposed means to secure said electrodes in surface contact between said terminal plates; of a bushing of fibrous material for said securing means impregnated With a material adaptedto supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated with a sealing compound covering the exposed surfaces of said couple between said terminal plates; said bushing, terminal plates and said layer cooperating to seal said couple.

5. In electric current rectifers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple comprising a centrally apertured electrode of relatively electropositive material, another centrally apertured electrode having a surface of a relatively electronegative material including at least one element chosen from the group sulphur, selenium and tellurium, terminal plates disposed on the ends of said couple, and a centrally disposed bolt to secure said electrodes in surface contact between said terminal plates; of a bushing of rlbrous material surrounding said bolt impregnated with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated with a sealing compound covering the exposed surfaces of said couple between said terminal plates; said bushing, terminal plates and said layer cooperating to seal said couple.

6. In electric current rectifiers and the like, 0f the dry surface contact variety, the combination with a unilaterally conductive couple comprising a relatively electropositive electrode, another electrode having a surface of a relatively electronegative material including at least onev element chosen from the group sulphur, selenium and tellurium; of a centrally disposed tube of brous material impregnated with a material adapted to supply to said'couple duringoperation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated with a plasticized lacquer covering the exposed surfaces of said couple, the vapor supplied by said centrally disposed tube during operation of said couple and said layer cooperating to seal said couple.

'7. In electric current rectifiers and the like, of the dry surface contact variety,rthe combination with a unilaterally conductive couple comprising a centrally apertured electrode of relatively electropositive material, another centrallyapertured electrode having .a surface of a relatively electronegative material including at least one element chosen from the group sulphur, selenium and tellurium, terminal plates disposed on the ends of said couple, and centrally disposed means to secure said electrodes in surface contact between said terminal plates; of a bushing of fibrous material for said securing means impregnated with with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fabric material impregnated with a plasticized lacquer covering the exposed surfaces of said couple between said terminal plates; said bushing terminal plates and said layer cooperating to seal said couple.

8. In a unilaterally conductive couple comprising a centrally apertured electrode of'v relative electropositive material, a centrally apertured electrode having a surface of relatively electronegative material including at least one of the elements sulphur, selenium and tellurium in surface contact with said first-mentioned electrode, terminal plates disposed on the ends of said couple, and a clamping bolt transf'lXing said terminal plates and said electrodes; the combination comprising a collar of fibrous material impreg- .nated with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of fibrous thread impregnated with a plasticized lacquer covering the exposed surfaces of said couple between said terminal plates, the vapor supplied by said collar during operation of said couple cooperating with said layer to seal said couple.

9. In a unilaterally conductive couple comprising a centrally apertured electrode of relatively electropositive material, a centrally apertured electrode having a surface of relatively electronegative material including at least one of the elements sulphur, selenium and tellurium in surface contact with said mst-mentioned electrode, terminal plates disposed on the ends of said couple, and a clamping bolt transiixing said terminal plates and said electrodes; the combination comprising a bushing of fibrous material impregnated with a material adapted to supply to said couple during operation thereof a vapor of at least one of the elements sulphur, selenium and tellurium, and a layer of brous thread impregnated with a plasticized lacquer covering the exposed surfaces of said couple between said terminal plates, said bushing being disposed be- 'tween said terminal plates and surrounding said bolt and cooperating with said layer and said terminal plates to seal said couple.

10. In electric current rectiiiers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple coxn.

prising an electropositive electrode, an electronegative material, and an inverse current-blocking film at their junction consisting of an electrochemically formed compound; 'of an internally disposed tube of fibrous material impreg- Ynated with a material adapted to`supply to said pregnated with a material `adapted vtosupply tosaid couple durins operation thereof ja vapor 'of at least one vof the elementssulphur, selenium and tellurium.

12. In a unilaterally conductive couple a bushing for a transfixing assembly bolt formed of fibrous material and impregnated with a material adapted to supply to said couple a vapor of at least one of the elements sulphur, selenium andtellurium. l

13. In a unilaterally conductive couple utilizing a centrally disposed assembly bolt, av bushing surrounding said bolt formed of flbrousmaterial and impregnated with a material adapted to supply to the said couple during operation thereof -a vapor` of at least one ofthe elements sulphur, selenium and tellurium.

14. In electric current rectifiers and the like, of the dry surface contact variety, the combination with a unilaterally conductive couple comprising a relatively electropositive electrode, another electrode having a surface of a relatively electronegative material, each of which is adapted to supply at least one element for the electromechanical formation and maintenance of a compound constituting an inverse current-blocking film at their junction; of a core of fibrous ma terial impregnated with a material adapted ,to supply to said couple duringA operation thereof a vapor of at leastone of said elements, and,a layer of fibrous material impregnated witha sealing compound covering the exposed surfaces of said couple. Y

15. In electric current rectiflers and the like, of the-dry surface contact variety, the combination with a unilaterally conductive couple comprisinga relatively electropositive electrode, an-

other electrode having a surface of a relatively electronegative material including atleast one element chosen from the group sulphur, selenium and tellurium; of a core of fibrous material im"- v pregnated with a'material adapted to supply -to said couple during operation thereof a vapor of at least one ofthe elements sulphur, selenium and tellurium, and a layer of fibrous material im? pregnated with a sealing compound covering the .I I

.exposed surfaces of said couple. 

